JPH11102545A - Information processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an information processor which, in order to control the parallelism between a plane on which a plurality of probes are provided and a recording medium surface, can maintain the parallelism between the probe plane and the recording medium surface with a high precision by using a simple construction. SOLUTION: A plurality of probes 101, which scan a recording medium 102 with probe needles and write and read information by physical interactions are arranged in a plane 2-dimensionally. A position control means, which controls the parallelism between the probe plane and the surface of the recording medium, is provided. The position control means has a probe with a cantilever structure having a piezoelectric resistance element, a resistance measuring means 107, which measures the resistance of the piezoelectric resistance element, an actuator, which controls the relative position between the probe and the recording medium in accordance with the measured resistance and a laser 110, which emits beams to the probe and the recording medium simultaneously. The resistance, which is changed by the laser emission, is measured by the resistance measuring means to control the parallelism between the probe plane and the recording medium surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording / reproducing apparatus utilizing an electrical phenomenon caused by applying a voltage between a probe and a sample and bringing the sample and the sample close to each other, and more particularly, to a device in which a plurality of probes are arranged in a plane. The present invention relates to an information processing apparatus which is provided two-dimensionally and has position control means for controlling two planes of a probe plane and a recording medium surface in parallel when recording and reproducing information.

[0002]

2. Description of the Related Art In recent years, a probe is brought closer to a sample, and a physical probe (tunnel phenomenon, atomic force, or the like) generated at that time is used to directly observe a material surface and an electronic structure near the surface. Microscopes (hereinafter abbreviated as SPMs) have been developed, and real-space images of various physical quantities, whether single-crystal or amorphous, can be measured with high resolution. In the industrial field, in recent years, attention has been paid to the principle of high resolution of the atomic or molecular size of SPM and disclosed in JP-A-63-16155.
As disclosed in Japanese Patent Publication No. 2 and JP-A-63-161553, application and practical application to an information recording / reproducing apparatus by using a recording layer in a medium have been energetically advanced. When applied to an information recording / reproducing apparatus as described above, parallel processing (multiplication) of a plurality of probes is progressing in order to improve the transfer rate. Also, a probe fabrication process for that purpose is being studied using a conventional semiconductor process or the like.

[0003]

When a recording / reproducing system as described above is constructed, for example, in order to obtain a transfer speed of about 200 Mbps, 100 kbps per line is required.
Even if these probes are used, 2000 probes are required. For example, 2000 probes are manufactured on the same substrate by using a semiconductor process. However, control of the distance between the medium surface and the probe substrate is indispensable in order to match the distance at which all the probes can interact with the medium. This can be realized by, for example, providing a measurement mechanism for measuring the distance between the probe substrate and the recording medium on the probe substrate, and keeping the distance constant by feedback control. By the way, when such distance measurement is performed at a plurality of points at the same time, in the optical lever type AFM conventionally used,
It is necessary to configure a plurality of optical detection systems, and the entire system is complicated and large, so that the information recording / reproducing apparatus becomes large and the production is difficult. Was.

Accordingly, the present invention solves the above-mentioned problems in the prior art. When controlling two planes, that is, a plane on which a plurality of probes are arranged and a surface of a recording medium, in parallel, the probe plane and the probe plane have a simple structure. It is an object of the present invention to provide an information processing apparatus capable of keeping the two planes parallel to the surface of a recording medium with high accuracy.

[0005]

In order to solve the above-mentioned problems, the present invention is characterized in that the information processing apparatus is configured as follows. That is, the information processing apparatus of the present invention scans the probe with respect to the recording medium, and a plurality of probes for writing and reading information by physical interaction are two-dimensionally arranged in a plane, and the information What is claimed is: 1. An information processing apparatus comprising: a position control unit for controlling two planes of a probe plane and a recording medium surface in parallel at the time of recording / reproduction, wherein said position control unit has a cantilever structure having a piezoresistor. A probe, a resistance measuring unit for measuring a resistance value of the piezoresistor, an actuator for controlling a position between the probe and the recording medium by a resistance value of the piezoresistor, and simultaneously irradiating the probe and the recording medium A resistance value of the piezoresistor, which is changed by irradiation of the laser, is detected by the resistance measuring means, and the probe plane and the recording surface are recorded. 2 of the body surface
It is characterized in that the planes are controlled in parallel. Further, in the information processing apparatus of the present invention, the probe in the position control means includes at least three position detection probes,
The three position detection probes are arranged at positions not on the same straight line in a two-dimensionally arranged probe plane. Further, the information processing apparatus of the present invention is characterized in that the writing of the information is performed by means for applying an electric bias between the probe and the recording medium. Further, the information processing apparatus according to the present invention is characterized in that the physical interaction is an electric current.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention uses a piezoresistor, detects the resistance of the piezoresistor that changes by laser irradiation by the resistance measuring means, and records the resistance value on the probe plane and the recording. By controlling the two planes in parallel with the medium surface, the structure can be simplified as compared with the conventional displacement detection by optical lever or optical interference. By adopting a configuration in which the above-described position detection probes are arranged at positions that are not on the same straight line in the plane where the probes are arranged, the parallelism between the two planes of the probe plane and the recording medium surface is maintained with high accuracy. It becomes possible.

[0007]

Embodiments of the present invention will be described below. [Embodiment 1] FIG. 1 shows the configuration of a positioning apparatus according to Embodiment 1 of the present invention. Reference numeral 101 denotes a displacement detection probe having a displacement system using a piezoresistor, which has a cantilever structure. Details of the structure will be described later. The change in the electric resistance value of the probe is measured by the connected resistance measuring unit 107. As will be described later, since the measured value indicates the distance between the medium substrate 102 and the probe, the control unit 106 at the subsequent stage controls the operation of the approach control unit 108 using the measured value. The approach control unit 108 has an actuator (in this embodiment, a stacked piezoelectric actuator is used on the probe side), and determines the distance between the medium substrate 102 and the probe by actually driving the actuator. In this embodiment, conventional PID control is used as a control method. The probe 101 is irradiated with light by a laser 110 in order to increase the carrier density inside the piezoresistor. In this embodiment, a semiconductor laser having a wavelength of 630 nm is used. The stage 103 is scanned by applying a scanning signal output from the scanning signal generation unit 105 to a stage actuator (in this embodiment, a laminated piezoelectric actuator is used) as a driving signal through an amplifier 104. The scanning signal generation unit 105 is controlled by the control unit 106 to set the sweep width, set the sweep speed, and control the positioning to a designated place.

FIG. 2 shows the structure of the displacement detection probe 101 of FIG. The probe 101 is a cantilever and has a probe 201 at the tip. This probe has a lever formed by forming a p-type piezoresistor 204 on an n-type Si substrate, and its structure is as shown in the figure below. The method for producing this probe is described in JP-A-5-19.
It was formed using the same process as that using an SOI substrate disclosed in Japanese Patent No. 6458. 203 is a substrate and a cantilever arm, 204 is a piezoresistor, 201 is a probe, 205 is an insulator protective layer, and 202 is a metal wiring pattern. L indicates the effective length of the cantilever, W indicates 1/2 of the effective width, and H indicates the thickness of the lever. The magnitude changes the mechanical properties (elastic constant and resonance frequency) of the lever and also affects the magnitude of the piezoresistance. The probe used in this example is W = 20 μm, L =
50 μm, H = 2 μm, thickness of piezoresistor = 0.2
μm, resistance value when no stress works R _init = 14 kΩ
(0.01% variation between probes). The height of the probe was 2 μm, and the resonance frequency of the entire lever was 120 kHz in the first mode of free bending. When displacement is measured by resistance using such a probe, a bridge circuit is generally used. As shown in FIG. 8, the change in the resistance value (Rs) to be measured is to be measured by the change in the potential difference between the points A and B.
The potential difference between the points A and B is detected by being amplified to a required magnification by a differential amplifier at the subsequent stage. At this time, in order to obtain a sufficient magnification, an initial state (a state in which the resistance does not change in the probe). In ()), it is desirable that the potential difference between points A and B is zero. In the case of actual measurement, a resistor for measuring a resistance change is inserted into a bridge as shown in FIG.

Next, the principle of performing position detection using such a probe will be described with reference to FIG. Generally, a resistor changes its resistance value by heat or light. In the case of using light, the resistance value decreases because the carrier density inside the piezoresistor increases due to the light. Further, depending on the rise in temperature, the characteristics vary depending on the substance of the resistor. In the case of a metal resistor or the like, the resistance value increases with an increase in temperature. This is a type in which lattice vibration becomes more intense due to a rise in temperature, and impedes the movement of electrons, which are current. On the other hand, in the case of a semiconductor or the like, there is a heat-active type in which a current easily flows because the amount of charge as a carrier increases due to a rise in temperature. Since the resistor of the probe used in this embodiment is a P-type semiconductor, it is considered that the latter phenomenon of thermal activation occurs predominantly.
That is, the resistance value of the piezoresistor changes in the direction of decreasing with the temperature rise of the probe.

With the configuration as in the present embodiment, the probe is irradiated with laser light, and the piezoresistor of the probe has an increased carrier density due to photoexcitation or thermal excitation accompanying a rise in temperature, and the resistance is reduced. However, as shown in FIG. 4, since the irradiated light is a coherent laser light, the light reflects on the medium substrate and the probe, and forms a standing wave between the probe and the substrate. That is, the light intensity shows a steady distribution in the direction perpendicular to the plane. Therefore, when the piezoresistive probe is inserted in such a place, as shown in the figure, it can be seen that the resistance value changes according to the distance from the medium substrate, that is, according to the light intensity.

FIG. 5 shows a change in resistance value when the probe is actually brought close to the medium. The probe position on the horizontal axis is a direction approaching the probe as going to the right of the graph. The resistance value changes in a wavy manner according to the change in distance. The wavelength of this wave is equal to the repetition length of the standing wave, and the wavelength λ of the laser light
(670 nm), which is half the length (335 nm). When the probe position is moved closer to the medium, the distance L
It changes greatly at ₀ . This is because the probe, which is disposed at the tip of the probe, comes into contact with the medium and the lever bends, causing a large change in resistance. Also, L ₀
The reason why the resistance value gradually increases while waving at a position smaller than that is due to heat exchange mediated by atmospheric molecules between the probe and the medium as they approach. The probe whose heat has been deprived of the medium by the approach causes a temperature drop, and consequently changes in a direction in which the piezoresistance becomes larger.

Next, the position is measured from this signal change.
First, L ₀ in the upper part of FIG. 5 is detected, and then the number of waves is counted from that position, and the position can be measured in units of λ / 2. For example, the number of peaks and valleys in a direction away from the contact position L ₀ as shown above in FIG. 5 1,2,3, ·· N, N + 1, N +
2, and put the ..., the position of the N-th of the mountain (or valley) is measured probe from the _{L 0 (N-1) λ} / 2~Nλ /
It can be seen that there is a distance of 2 plus the height of the probe portion (2 μm in the case of the present embodiment). In this embodiment, the search for mountains and valleys is performed as shown in FIG.
As shown in the figure below, the measurement was performed using a differential value according to the position of the resistor. By searching for a point where the differential value becomes 0 and counting the point, the position can be measured with an accuracy of λ / 2 (335 nm in this embodiment). However,
In this measurement, it is not particularly important to count the points at which the differential value becomes 0, and even if the points having a specific value of the differential value, the maximum point, etc. are counted, there is no substantial effect on the present invention.

[Embodiment 2] In Embodiment 2, the position control is performed using the configuration used in Embodiment 1. First, as in the first embodiment, the positions of the probe and the medium are set. That is, the distance to be set is matched with the count number of valleys and λ / 2 as a unit. Next, the control unit 106 shown in FIG.
, The proximity control unit 108 was driven such that the differential value of the resistance value constantly became 0, and the distance between the probe media was controlled by PID control. In this embodiment, the distance is determined by setting the count number to 10 (3.015 μm to 3.350 μm).
m), the distance was fixed at that position. When the accuracy was measured by preparing another system capable of measuring the displacement of the probe due to interference by laser light, for example, the fluctuation was 1 nm or less, and it was found that the position could be fixed with high accuracy. Further, in the present embodiment, the reference position of the feedback is set to a point where the differential value of the resistance value becomes 0. However, the set value itself has no particular meaning, and may be a certain appropriate value or a maximum value. The second derivative of the resistance value may be used.

Embodiment 3 Embodiment 3 is an application of the present invention to a memory system. A probe substrate as shown in FIG. 6 was used. A probe 602 for position detection and a probe 603 for recording / reproduction characteristic of the present invention are arranged on the probe substrate 601. The recording medium substrate is set to face the probe substrate. FIG. 7 shows the relationship between the position detecting probe and the recording / reproducing probe. Reference numeral 703 denotes a medium substrate set to face the probe substrate, reference numeral 701 denotes a position detection probe, and reference numeral 702 denotes a recording / reproducing probe. The position detecting probe is irradiated with laser light 704. By adjusting the height of the probe and the like, the contact order of the probe with the medium when the two substrates are brought close can be adjusted.

In this embodiment, the relationship shown in FIG. 7 is used. That is, when both substrates approach, first, FIG.
The recording / reproducing probe comes into contact with the medium as shown in FIG.
Next, when the probe is further pushed, the probe of the position detection probe comes into contact. Recording and reproduction were performed by the method disclosed in JP-A-63-161552 and JP-A-63-161553. The probe of the recording / reproducing probe 702 has conductivity, and the probe is electrically connected to an external detection circuit. Wiring is performed so that a bias is applied to the medium through the probe and a current value is detected. As a recording medium, an organic compound having six monolayers formed by a Langmuir-Blodgett method using an organic compound having a conjugated π-electron system also described in JP-A-63-161552 or JP-A-63-161553. A thin film (LB film) was used. Recording was performed by applying a pulse voltage to the current detection probe in time series as described above. An applied waveform for recording was a triangular wave having a peak value of 3V. The reproduction was performed by applying a DC bias of 2 V to the substrate side and measuring the current. For recording and reproducing bits, the recording and reproducing probe is brought to a desired position on the medium while sweeping parallel to the surface direction of the medium, so that the bits can be recorded and reproduced.

Next, a procedure for keeping the probe substrate and the medium substrate parallel will be described. The position measurement is performed in substantially the same manner as in the first embodiment, but unlike the first embodiment, the position is not approached until the position detecting probe is brought into contact, and the contact point of the nearby recording / reproducing probe is used as the reference point. That is, a voltage is applied to the medium substrate in advance (read bias),
The moment when a current flows through a nearby recording / reproducing probe is defined as a position L _0.
From there, the number of waves of the resistance value waveform is counted. The counting method is the same as in the first embodiment. Example 2
With the control method exactly the same as that shown in (1), it is possible to perform feedback control of the pushing amount of the recording / reproducing probe from the contact point. With the above method, the distance between one position detection probe and the medium substrate can be controlled.
In the case of the present embodiment, three such position detection probes are arranged on the probe substrate so as not to be on the same straight line, and an approach actuator is installed at the position of the position detection probe, and three points on the substrate are used. Distance control was performed to maintain parallelism.

As a result, it is possible to prevent the two surfaces from becoming non-parallel due to the drift of the actuator, the parasitic vibration of the system, etc., and it is possible to keep all the recording / reproducing probes in stable contact with the medium substrate. The non-contact state of the probe during recording / reproduction can be avoided. Specifically, the value was ~ 0.01 when the parallel setting was not performed and the parallel control was performed only at the time of initialization, but was ~ 0.001 when the control of the present invention was performed, which is about 10 times. The improvement of the error rate was obtained. Finally, in the present embodiment, the laser beam was irradiated to the three probes by the external laser. However, in the case of the present invention, it is only necessary to irradiate coherent light (the light detection system is unnecessary). In the case where the integration and the density increase are performed by using the same, it is sufficiently possible to form them on the same substrate by using a surface emitting laser or the like. Further, since the interference of light is substantially measured, the accuracy can be improved by changing the wavelength of light.

[0018]

As described above, the present invention comprises a probe having a cantilever structure provided with a piezoresistor, and detects the resistance value of the piezoresistor, which changes by laser irradiation, by the resistance measuring means. By controlling the two planes of the probe plane and the recording medium surface in parallel, the structure can be simplified as compared with the conventional displacement detection by optical leverage or optical interference. The three or more position detection probes are arranged in a position where they are not on the same straight line in the plane where the probes are arranged, so that the two planes of the probe plane and the recording medium surface are arranged. Parallelism can be maintained with high precision.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a configuration of a position measurement and position control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a displacement detection probe of FIG.

FIG. 3 is a schematic diagram of a resistance measurement circuit.

FIG. 4 is a diagram showing a relationship between a probe, a medium substrate, and laser light.

FIG. 5 is a diagram showing a detected resistance waveform.

FIG. 6 is a schematic diagram of a multi-probe substrate used for an information processing device.

FIG. 7 is a diagram showing a relationship between a position detection probe and a recording / reproducing probe.

FIG. 8 is a view for explaining measurement of a sample resistance by a bridge circuit.

[Explanation of symbols]

 101: Displacement detection probe 102: Medium substrate 103: Stage 104: Amplifier 105: Scan signal generation unit 106: Control unit 107: Resistance measurement unit 108: Approach control unit 110: Laser 201: Probe 202: Metal wiring pattern 203: Substrate And cantilever arm 204: piezoresistor 205: insulator protective layer 601: probe substrate 602: probe for position detection 603: probe for recording and reproduction 701: probe for position detection 702: probe for recording and reproduction 703: medium substrate 704: Laser light

Claims (4)

[Claims] A plurality of probes for scanning a recording medium with a probe and writing and reading information by physical interaction thereof are two-dimensionally arranged in a plane. An information processing apparatus comprising: a position control means for controlling two planes of a probe plane and a recording medium surface in parallel, wherein the position control means comprises a probe having a cantilever structure having a piezoresistor; A resistance measuring unit for measuring a resistance value of a resistor; an actuator for controlling a position between the probe and the recording medium by a resistance value of the piezoresistor; and a laser for simultaneously irradiating the probe and the recording medium. Then, the resistance value of the piezoresistor, which changes due to the laser irradiation, is detected by the resistance measuring means, and the two planes of the probe plane and the recording medium surface are flattened. An information processing apparatus characterized in that control is performed in rows. 2. The probe in said position control means comprises at least three position detecting probes, and said three position detecting probes are arranged at positions not on the same straight line in a two-dimensionally arranged probe plane. The information processing apparatus according to claim 1, wherein 3. The information processing apparatus according to claim 1, wherein the writing of the information is performed by means for applying an electric bias between the probe and the recording medium. Information processing device. 4. The information processing apparatus according to claim 1, wherein the physical interaction is a current.